Automatic determination of parting directions,parting lines and surfaces for two-piece permanent molds

Minimization of surface area/volume of undercuts, flatness of parting surface and minimization of draw depth play a major role to determine the best pair of parting directions for two-piece permanent molds. In most of the earlier attempts a combined effect of the three factors was not considered. Moreover with the increasing complexity of molded product geometry, heuristic and feature-based approaches may prove inefficient. In this paper the combined affect of minimized surface area of undercut, flatness of parting surface and minimized draw depth is considered for the determination of best parting direction, parting line and surface for a two-piece permanent molded component. Tessellated geometry of the component is used as input.     

Analyzing the Structure and Evolution of Massive Telecom Graphs

With the ever-growing competition in telecommunications markets, operators have to increasingly rely on business intelligence to offer the right incentives to their customers. Existing approaches for telecom business intelligence have almost solely focused on the individual behavior of customers. In this paper, we use the call detail records of a mobile operator to construct call graphs, that is, graphs induced by people calling each other. We determine the structural properties of these graphs and also introduce the Treasure-Hunt model to describe the shape of mobile call graphs. Moreover, we determine how the structure of these call graphs evolve over time. Finally, since short messaging service (SMS) is becoming a preferred mode of communication among many sections of the society, we study the properties of the SMS graph. Our analysis indicates several interesting similarities and differences between the SMS graph and the corresponding call graph. We believe that our analysis techniques can allow telecom operators to better understand the social behavior of their customers and potentially provide major insights for designing effective incentives.     

Exact analysis of adaptive go-back-NARQ scheme

The analysis of the adaptive go-back-N scheme reported by Yao contains some mathematical inaccuracies, which have further been used by Annamalai et al. The authors provide an exact analysis of the adaptive scheme under identical operating conditions     

A fully monolithic 260-/spl mu/W, 1-GHz subthreshold low noise amplifier

A micro-power complementary metal oxide semiconductor (CMOS) low-noise amplifier (LNA) is presented based on subthreshold MOS operation in the GHz range. The LNA is fabricated in an 0.18-/spl mu/m CMOS process and has a gain of 13.6 dB at 1 GHz while drawing 260 /spl mu/A from a 1-V supply. An unrestrained bias technique, that automatically increases bias currents at high input power levels, is used to raise the input P1dB to -0.2 dBm. The LNA has a measured noise figure of 4.6 dB and an IIP3 of 7.2 dBm.     

Mixed valency character of bismuth in ferrite lattices

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

Determination of Physical Parameters of Stiffened Plates using Genetic Algorithm

An investigation on stiffened isotropic and composite plates has been conducted to determine the geometric and material parameters for the plate, as well as the stiffener from experimental modal data and finite element predictions using a genetic algorithm (GA). The problem is formulated as a global minimization of the error function defined by the difference in undamped eigenvalues and eigenvectors, as predicted from the finite-element modeling to that obtained experimentally. The parameter estimation problem is solved using a GA implementing selection, crossover, and mutation operators to obtain the global minimum solution. Because stiffeners contribute substantially to the overall rigidity of the plate assembly, their position, physical properties, and orientation create considerable variation of the modal properties, as compared to the bare plate with similar construction. This makes each of the stiffened plate identification problems rather unique. GAs have been the subject of considerable interest in providing a robust search procedure for a global optimum solution for such difficult minimization problems. The method is demonstrated on a few simulated examples on stiffened plates to investigate the uniqueness and convergence of results. The methodology, although slow in execution, is found to be very robust, even in the presence of noise, for isolating interesting zones of the search space. Unlike many traditional optimization techniques, it does not get stuck at a particular local minimum due to its parallelism.     

On the dispersion equation of Love waves in a porous layer

Summary The paper is concerned with the propagation of Love waves in a porous layer over an inhomogeneous half-space due to a point source. The dispersion equation for Love waves in a porous layer has been derived. The effects of porosity and inhomogeneity in the half-space have been shown graphically on the dispersion curves. The theory pointed out by Biot for the porous medium has been applied to solve the problem with the help of Green's function technique.With 4 Figures     

Shock deformation of coarse grain alumina above Hugoniot elastic limit

Symmetric shock experiments were conducted on a 10 μm grain size coarse alumina ceramic with a gas gun to identify its Hugoniot elastic limit (HEL). To understand the damage initiation and their subsequent growth mechanisms in coarse grain alumina subjected to shock impact at levels much above the HEL, additional asymmetric shock recovery experiments with the same gas gun were then deliberately conducted on the same alumina at shock pressure levels more than three times as high as the HEL and the fragments collected by a dedicated catcher system. Detailed characterization of the shock recovered alumina fragments by X-ray diffraction, nanoindentation, scanning electron microscopy, field emission scanning electron microscopy and transmission electron microscopy were utilized to understand the nature and process of failure initiation, incubational growth, coalescence and propagation leading to fragmentation. Based on these data a new qualitative damage model was developed to explain the deformation mechanism.